Role of femtosecond pulses in distinguishing third- and fifth-order nonlinearity for semiconductor-doped glasses

We report Z-scan experiments at a frequency below the band gap of semiconductor-doped glasses using 100 fs laser pulses. A large contribution from the positive third-order nonlinearity is observed in complete contrast with the picosecond z-scan experiments. The third- and fifth-order nonlinearity for semiconductor-doped glasses can be estimated from z-scans for ps and fs pulses. © 2001 American Institute of Physics.